Iolite Quality Factors

The cutter took full advantage of this iolite’s color and transparency, fashioning it into a uniquely carved gem, ready for use in jewelry. – Lydia Dyer, Gem courtesy John Dyer & Co.

Affordable and attractive, iolite can be used in many types of jewelry. It’s sometimes found in large sizes and beautiful, intense colors that satisfy even the most discriminating colored gemstone connoisseur.

This attractive iolite was skillfully cut to show its best color face-up.

Clarity
Iolite is commonly transparent, with relatively few inclusions. It can be found in all shapes and has even been carved to beautiful effect.

Iolite can contain inclusions that cause various phenomena. Occasionally, iolites with long, parallel, tubular inclusions are found. When the cut is oriented properly, these stones yield cat’s-eye gems.

Iolite containing numerous metallic, plate-like inclusions can be cut to display a sparkly effect known as aventurescence. When the platelets are brownish or reddish in color, the gem might be marketed as “bloodshot” iolite.

The brownish and reddish inclusions make this a “bloodshot” iolite.

Cut
Because it is commonly transparent with relatively few inclusions, iolite is most often faceted. However, iolites can be cut into cabochons or carvings as well. They are frequently seen as beads, especially when the material is of somewhat lower quality.

Carat Weight
The size range for a fashioned iolite is anywhere from 1 to 10 carats, but fine iolites over five carats are rare.

Learn More About Iolite

Explore iolite history, research, quality factors, and more in the GIA Gem Encyclopedia.